2025 Volume 81 Issue 16 Article ID: 24-16034
The Shimabara Peninsula in Nagasaki Prefecture has been facing a significant issue of groundwater contamination due to nitrate-nitrogen. In response, the prefecture launched the Shimabara Peninsula Nitrogen Loading Reduction Plan in October 2006 and has been implementing various measures to address this problem. This study utilized The MannKendall test to analyze the trend of change in nitrate-nitrogen concentrations based on data disclosed by the prefectural government and water source wells measured by the water-works department of Shimabara City. According to the data collected by the prefecture, it can be said that nitrate-nitrogen pollution in the last eight years has not shown any improvement trend. The factors that led to the reduction of nitrate-nitrogen concentrations in earlier years should be carefully examined. The concentration trends in the source well data of Shimabara City indicate that the situation is not improving and is approaching a serious situation.
